2 tornadoes sneaked in with heavy storm

Twisters touched down in Downers Grove, Mount Prospect, National Weather Service says

By Cynthia Dizikes | Tribune reporterJune 22, 2011

The line of mighty storms that blew through the Chicago area Tuesday evening unleashed heavy rain, thunder and lightning, fierce winds and two small tornadoes that carved paths through parts of Downers Grove and Mount Prospect.

Investigators with the National Weather Service determined Wednesday that the tornado in Mount Prospect traveled a path about 200 yards wide over some two miles, snapping and uprooting trees along the route.

The tornado was rated EF1 (on the Enhanced Fujita scale for measuring tornadoes), meaning it carried winds of 86 to 110 miles per hour, according to National Weather Service meteorologist Mark Ratzer.

A similar pattern occurred in Downers Grove, where a tornado touched down near Sunnydale Park in Woodridge and sped northeast to 55th and Main streets in Downers Grove. The path of that tornado was also about 200 yards wide, covering 2.1 miles, the weather service said.

Most of the damage through the north and northwest suburbs was the result strong straight-line winds that in some cases were clocked in excess of 80 mph, Ratzer said.

Tuesday’s humid air combined with a strong jet stream aloft and a cold front rolling in from the west to produce storms reaching up over 50,000 feet, meteorologists said.

“This was a fascinating storm to watch,” said WGN meteorologist Jim Ramsey. “You had a system that sailed through very quickly and produced a variety of dangerous aspects like tornadoes and straight-line winds.”

The combination of the unstable warm air and strong mid- and upper-level winds brought powerful gusts through the Chicago area, Ratzer said.

“Storms happen all the time,” Ratzer said. But Tuesday’s setup “was a recipe for severe thunderstorms.”